Intravascular system for occluded blood vessels and guidewire for use therein

ABSTRACT

A system and method for opening a lumen in an occluded blood vessel, e.g., a coronary bypass graft, of a living being. The system comprises an atherectomy catheter having a working head, e.g., a rotary impacting impeller, and a debris extraction sub-system. The atherectomy catheter is located within a guide catheter. The working head is arranged to operate on, e.g., impact, the occlusive material in the occluded vessel to open a lumen therein, whereupon some debris may be produced. The debris extraction sub-system introduces an infusate liquid at a first flow rate adjacent the working head and withdraws that liquid and some blood at a second and higher flow rate, through the guide catheter to create a differential flow adjacent the working head, whereupon the debris is withdrawn in the infusate liquid and blood for collection outside the being&#39;s body. The introduction of the infusate liquid may also be used to establish an unbalanced flow adjacent the working head to enable the atherectomy catheter to be steered hydrodynamically. A guide wire having an inflatable balloon on its distal end may be used with the atherectomy catheter to block the flow of debris distally, while enabling distal tissues to be perfused with an oxygenating liquid. At least one flow control port may be provided in the guide catheter to prevent collapse of the vessel being revascularized. A cradle is provided to fix the guide catheter and guide wire in position within the body of the being while enabling the atherectomy catheter to be advanced along the guide wire and through the guide catheter. The guide catheter includes a wear resistant coating and is constructed so that its distal end includes plural sections of different outside diameters, with the distal most section being of the smallest outside diameter. A control console is provided to establish various modes of operation of the system based on manual inputs via switches or voice commands via voice recognition circuitry. A video panel displays the various modes of operation and instructions to the operator.

RELATED APPLICATIONS

[0001] This application is a Divisional of U.S. patent application Ser.No. 09/690,976, filed on Oct. 18, 2000, entitled System and Method ofUse for Revascularizing Stenotic Bypass Grafts and Other Occluded BloodVessels, which in turn is a Continuation-In-Part of U.S. patentapplication Ser. No. 09/594,131, filed on Jun. 14, 2000, entitled Systemand Method of Use for Revascularizing Stenotic Bypass Grafts and OtherOccluded Blood Vessels, which in turn is a Continuation of U.S. patentapplication Ser. No. 09/233,712, filed on Jan. 19, 1999, entitledImproved System And Method Of Use For Revascularizing Stenotic BypassGrafts And Other Occluded Blood Vessels, now U.S. Pat. No. 6,080,170,which in turn is a Continuation-In-Part of U.S. patent application Ser.No. 08/900,598, filed on Jul. 25, 1997, entitled System And Method OfUse For Revascularizing Stenotic Bypass Grafts And Other Blood Vessels,now U.S. Pat. No. 5,879,361, which in turn is a Continuation-In-Part ofU.S. application Ser. No. 08/690,438, filed on Jul. 26, 1996, entitledSystem And Method Of Use For Revascularizing Stenotic Bypass Grafts AndOther Blood Vessels, now U.S. Pat. No. 5,779,721, all of which areassigned to the same assignee as this invention, and whose disclosuresare incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] This application relates generally to medical instruments andmethods of use to remove occlusive material from a vessel, duct or lumenwithin the body of a living being.

[0003] Catheter instruments have been suggested or disclosed in thepatent literature for effecting non-invasive or minimally invasiverevascularization of occluded arteries. For example, in U.S. Pat. No.4,445,509 there is disclosed a recanalization catheter designedspecifically for cutting away hard, abnormal deposits, such asatherosclerotic plaque, from the inside of an artery, while supposedlypreserving the soft arterial tissue. That recanalizing catheter includesa sharp-edged, multi-fluted, rotating cutting tip mounted at the distalend of the catheter and arranged to be rotated by a flexible drive shaftextending down the center of the catheter. The rotation of the cuttinghead is stated as producing a “differential cutting” effect, whereuponrelatively hard deposits are cut away from relatively soft tissue.Suction ports are provided to pull the hard particles produced by thecutting action into the catheter for removal at the proximal end thereofso that such particles do not flow distally of the catheter where theycould have an adverse effect on the patients' body.

[0004] In U.S. Pat. No. 4,700,705, which is assigned to the sameassignee as this invention and whose disclosure is incorporated byreference herein, there are disclosed and claimed catheters and methodsof use for effecting the opening of a vessel, duct or lumen, such as theopening of a atherosclerotic restriction (partial or total occlusion) inan artery. These catheters are elongated flexible members of sufficientflexibility to enable them to be readily passed through the body of thepatient to the situs of the atherosclerotic plaque in the artery to beopened. A working head is mounted at the distal end of the catheter andis arranged for high-speed rotation about the longitudinal axis of thecatheter. In some embodiments the catheter may eject fluid at theworking head to expedite the restriction-opening procedure.

[0005] In U.S. Pat. No. 4,747,821, which is also assigned to the sameassignee as this invention and whose disclosure is incorporated byreference herein, there is disclosed and claimed other cathetersparticularly suited for revascularization of arteries. Each of thosecatheters includes a rotary working head having at least one non-sharpimpacting surface to effect material removal without cutting. Moreover,those catheters are arranged to eject fluid adjacent the working head toexpedite the revascularization procedure. In particular, the rotation ofthe working head produces a powerful, toroidal shaped vortex contiguouswith the working head which has the effect of recirculating anyparticles that may have been broken off from the material forming thearterial restriction so that the working head repeatedly impacts thoseparticles to reduce their size.

[0006] In U.S. Pat. No. 5,042,984, which is also assigned to the sameassignee as this invention and whose disclosure is incorporated byreference herein, there are disclosed and claimed catheters whoseworking heads include impacting surfaces of differing aggressivenesswhich may be selectively brought into engagement with the restriction tobe opened. Such catheters also make use of exiting jets of liquid asdescribed above.

[0007] Other atherectomy devices for enlarging an opening in a bloodvessel have been disclosed and claimed in the following U.S. Pat. No.4,589,412 (which is assigned to the same assignee as this invention andwhose disclosure is incorporated by reference herein); U.S. Pat. Nos.4,631,052; 4,686,982 (which is assigned to the same assignee as thisinvention and whose disclosure is incorporated by reference herein);U.S. Pat. No. 4,749,376 (which is assigned to the same assignee as thisinvention and whose disclosure is incorporated by reference herein);U.S. Pat. Nos. 4,790,813; 5,009,659; 5,074,841; 5,282,484; 5,366,463;5,368,603; 5,402,790; 5,423,742; and 5,429,136.

[0008] Some rotary atherectomy devices are in use in this country forrevascularizing occluded arteries. However, their use is limited to somevery selected applications. Thus, in many instances a vascular occlusionof a coronary artery can only be treated by coronary bypass surgerywherein a graft, e.g., a saphenous vein section and/or mammary arterysection, is surgically shunted across the occluded coronary artery.Unfortunately a significant percentage of bypass surgical grafts becomere-occluded over time. Thus, the re-occluded graft has to be eitherbypassed by another graft (i.e., second bypass surgery), or there-occluded graft has to be revascularized (i.e., its lumen reopened) bysome intravascular procedure. If the occluded graft is not totallyoccluded, balloon angioplasty may be indicated to reopen the graft.Where, however, the graft is totally occluded or heavily occluded byfrangible deposits balloon angioplasty is unavailable. Thus, ifrevascularization of such a graft is desired, resort may be to rotaryatherectomy.

[0009] One currently available rotary atherectomy device is theROTOBLATOR® System of Heart Technology, Inc. That system utilizes acatheter having a diamond coated elliptical burr which is rotated at ahigh rate of speed, e.g., up to 190,000 rpm. The burr serves to breakthe atherosclerotic plaque into fine particles which are allowed toremain in the patient's body for disposal by the patient'sreticuloendothelial system.

[0010] As is known to those skilled in the art, one problem with arotary atherectomy device is that unless the debris produced is so smalland benign that it can be left within the patient's vascular systemthere must be some means to ensure that the debris does not flowupstream into the aorta during the procedure or into the downstreamartery graft at the break-through point when the device comes out thedistal side of a total occlusion, since either action could present asignificant hazard to the patient. In particular, the former route risksstroke, the later route risks local ischemia of heart muscle when debrisblocks off small arteries.

[0011] Thus, the collection and/or aspiration of debris produced duringthe revascularization of occluded arterial bypass grafts or other bloodvessels is getting considerable attention in the medical arts. Forexample, Possis Medical, Inc., the assignee of U.S. Pat. Nos. 5,370,609and 5,496,267, provides catheter devices designated as the ANGIOJETRapid Thrombolectomy System and the ANGIOJET Rheolytic ThrombolectomySystem. These devices are presumably constructed in accordance withthose patents and are believed to be presently undergoing clinicaltrials. The catheter devices disclosed in those patents utilize highvelocity jets of saline to abrade the blockage. In particular, thepatents disclose utilizing the momentum of the saline jets to create alocal vacuum to entrain any particulate material produced by therevascularization procedure, with the momentum and the local positivepressure being sufficient to carry the saline and debris to a returncollection bag.

[0012] Another atherectomy device which is currently undergoing clinicaltrials is the Coronary TEC® System of Interventional Technologies, Inc.That device is believed to be the subject of U.S. Pat. No. 5,224,945,and basically comprises a catheter having a working head with microtomesharp blades for cutting plaque circumferentially. The excised plaque isextracted by suction through a central lumen in the catheter into anexteriorly-located vacuum bottle. No control of the quantity of flow ofthe debris-carrying fluid from the catheter is disclosed.

[0013] U.S. Pat. No. 5,030,201 (Palestran) discloses a system includingan expandable atherectomy catheter arranged to be rotated to cut throughan occluded artery to revascularize it. The atherectomy catheterincludes an expandable cutting head having plural elongated cuttingmembers which are mounted on a flexible torque tube incorporating avacuum or aspiration system for retrieval of excised material. Thecutting head is arranged to be rotated to cause the elongated members tocut away atheromatous material or blood clots. The atherectomy catheteris arranged to be inserted into the blood vessel through a coaxialdelivery catheter, also forming a part of the system. The mechanism foraspirating particles of atheromatous material or blood clots removed bythe elongated cutting members is disclosed as being in the form of avacuum port provided at the proximal end of either the deliverycatheter, the atherectomy catheter or a “retracting catheter” which alsoconstitutes a part of the system. Saline solution or some other irrigantis infused through one of the catheters of the device that is not beingused for aspiration. The infusion rate of the saline solution isbalanced with the aspiration rate to avoid any net removal of fluid fromthe vessel. In particular, the patent teaches that by balancing theinfusion rate of the saline solution to the aspiration rate, the netremoval of fluid from the vessel can be brought close to zero, therebyminimizing blood loss.

[0014] While the balancing of the infusion and aspiration flow rates tominimize blood loss may be desirable, such action does not insurepositive removal of all debris produced during the revascularizationprocedure.

[0015] Accordingly, a need exists for apparatus and a method of use torevascularize partially or totally occluded blood vessels, whilepositively assuring that any particles produced during therevascularization procedure are removed from the patient's body. In thecase of partially or totally occluded coronary bypass grafts, a needexists for intravascular atherectomy apparatus and methods of use foreffectively producing a lumen through the occlusion for the free flow ofblood, without the risk that any debris produced during the lumenopening procedure will enter into the aorta or downstream of theocclusion once it has been crossed or opened.

SUMMARY OF THE INVENTION

[0016] A system for opening a lumen in an occluded blood vessel, e.g., acoronary bypass graft, of a living being's vascular system locateddownstream of another blood vessel, e.g., the aorta, from which bloodwill flow to the occluded blood vessel. The system basically comprises aguide catheter, a lumen-opening catheter, a debris blocking member, anda fluid flow system.

[0017] The guide catheter has a distal end portion and at least oneblood entrance port located proximally of the distal end portion. Thelumen-opening catheter extends through the guide catheter to establish afluid flow passageway therebetween and has a working head, e.g., arotatable impacting member, for location immediately adjacent theocclusive material within the occluded blood vessel portion. The workinghead is arranged for operating on the occlusive material, e.g.,repeatedly impacting it, to open a lumen for the freer flow of bloodtherethrough. Some debris may be produced by the operation of theworking head.

[0018] The debris blocking member is located distally of the workinghead to prevent debris from flowing distally thereof.

[0019] The fluid flow system is arranged to introduce an infusate liquidat a first flow rate adjacent the working head and to withdraw thatliquid through the passageway between the guide catheter and the lumenopening catheter at a second and higher flow rate to create adifferential flow adjacent the working head, whereupon debris producedby the operation of the working head is withdrawn by the differentialflow and flows with the liquid proximally through the passageway forextraction.

[0020] The blood entrance port in the distal end portion of the guidecatheter is in communication with the passageway between the guidecatheter and the lumen opening catheter, whereupon blood from the patentblood vessel portion may enter for merger with the liquid and debrisflowing through that passageway.

[0021] The debris blocking member is an inflatable balloon is providedat the distal end of the instrument to physically block the egress ofany debris downstream of the apparatus. Perfusion means is preferablyprovided to inflate the balloon and to oxygenate downstream tissue whenthe balloon is inflated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Many of the attendant advantages of this invention will readilybe appreciated as the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings wherein:

[0023]FIG. 1 is a schematic diagram, partially in section, of a systemof the subject invention shown during the process of opening a lumen ina totally occluded coronary bypass graft so that blood can flowtherethrough;

[0024]FIG. 2 is an enlarged view, partially in section, of a portion ofthe system of FIG. 1 shown during the process of opening a lumen in theoccluded coronary bypass graft;

[0025]FIG. 3 is an even more greatly enlarged view, partially insection, of a portion of the system shown in FIG. 2;

[0026]FIG. 4 is a reduced isometric view of the portion of the systemshown in FIG. 3;

[0027]FIG. 5, is an illustration showing the apparatus of FIG. 1,partially in section, during the process of revascularizing a totallyoccluded femoral artery downstream of the profunda femoris;

[0028]FIGS. 6A and 6B together are an illustration of another embodimentof the system of this invention for revascularizing or opening a lumenin a coronary bypass graft;

[0029]FIG. 7 is an enlarged isometric illustration of a portion of aninstrument forming a component of the system shown in FIGS. 6A and 6Bduring the process of revascularizing a diseased bypass graft;

[0030]FIG. 8 is an enlarged longitudinal sectional view of the distalend of the instrument shown in FIG. 7;

[0031]FIG. 9A is an isometric view of a portion of another preferredembodiment of this invention making use of a guide catheter having atleast one flow regulation port to ensure that the vessel beingrevascularized does not collapse during the extraction of the debrisproduced by the revascularization;

[0032]FIG. 9B is an isometric view of another portion of the embodimentof the system shown in FIG. 9;

[0033]FIG. 10 is an enlarged isometric view of the distal end of theatherectomy catheter, guide catheter and guide wire of the embodiment ofFIG. 9A shown during revascularization of a coronary bypass graft, wherethe guide catheter tightly fits within the bypass graft;

[0034]FIG. 11 is a view similar to FIG. 10 but where the guide catheterfits loosely within the bypass graft;

[0035]FIG. 12 is a greatly enlarged longitudinal sectional view of thedistal end of an atherectomy catheter forming a part of the embodimentof the system of FIG. 9A;

[0036]FIG. 13 is an enlarged longitudinal sectional view of the proximalend of the atherectomy catheter of the system of FIG. 9A;

[0037]FIG. 14 is an enlarged longitudinal sectional view similar to FIG.8, but showing a modified guide wire and distally located balloon foruse with the systems of this invention;

[0038]FIG. 15 is a graph showing the four potential sizes and numbers offlow regulation ports for the guide catheter and their potential forprecluding collapse of the vessel being revascularized; and

[0039]FIG. 16 is a view similar to that of FIG. 10 but showing a methodof providing a stent in an occluded blood vessel section, e.g., a bypassgraft, to revascularize it, and with the debris extraction system makinguse of a guide catheter tightly engaging the wall of the blood vesselsection;

[0040]FIG. 17 is a view similar to that of FIG. 11 but showing a methodof providing a stent in an occluded blood vessel section, e.g., a bypassgraft, to revascularize it, and with the debris extraction system makinguse of a guide catheter not engaging the wall of the blood vesselsection;

[0041]FIG. 18 is an isometric view of a complete revascularizationsystem constructed in accordance with this invention, with portionsthereof being broken away to show various components of the system; and

[0042]FIG. 19 is a plan view of a coated guide wire having a balloonmounted thereon as used in the system of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0043] Referring now in greater detail to the various figures of thedrawings wherein like reference characters refer to like parts, there isshown at 20 in FIG. 1 a system for revascularizing or opening a lumenthrough a coronary bypass graft which has become occluded, such as bythe formation of a stenotic lesion or the build-up of plaque therein. Asused herein the term “occluded” is given its broadest interpretation.Thus, an “occluded” graft or blood vessel may be either totally blockedor only partially blocked (i.e., there is a passageway or lumen throughwhich some blood may flow).

[0044] The system 20 is arranged to be used for forming or enlarging alumen through any blood vessel within the body of a living being, e.g.,an occluded femoral artery downstream of the profunda femoris, notnecessarily an occluded coronary bypass graft or an occluded coronaryartery. In particular, the system 20 is arranged to produce a channel orlumen or to enlarge a lumen through the occlusive material within thevessel and to ensure that any particles of that material which areremoved or broken away, during the revascularization procedure areprevented from flowing into the contiguous vascular system. When thesystem 20 is used for revascularization of occluded coronary bypassgrafts, a primary application for the system 20, the debris produced isdrawn into the system for extracorporeal removal and is thus preventedfrom entering the aorta.

[0045] As can be seen in FIG. 1, the system 20 basically comprises an“atherectomy” catheter 22, a guide catheter 24, an introducer sheath 26,a drive sub-system 28, and a debris removal sub-system 30. Theatherectomy catheter 22 is in the form of an elongated flexible tubularbody member or jacket at the free or distal end of which is located arotatable working head 32. The working head 32 is generally similar tothat described in U.S. Pat. No. 4,747,821. Alternatively, the workinghead may be constructed in accordance with the teachings of U.S. Pat.Nos. 4,679,558,4,686,982,4,749,376,5,042,984, and 5,097,849, all ofwhich are also assigned to the same assignee as this invention, andwhose disclosures are also incorporated by reference herein. In fact,the working head may be any device for opening a lumen through theocclusive material.

[0046] In use the atherectomy catheter 22 is guided through the vascularsystem of the patient by the guide catheter 24 (which is conventionallyplaced) to the site of the vascular occlusion that has been determinedto exist, so that the rotary working head is located immediatelyadjacent the upstream end of the occlusion. In the embodiment shown inFIG. 1, the atherectomy catheter is located within a coronary bypassgraft 10 having an upstream end in fluid communication with the aorta12. The downstream end of the graft is not shown and is in fluidcommunication with the coronary artery being bypassed or with smallerarteries of the heart. In the example shown herein the graft 10 istotally occluded by an atherosclerotic lesion or plaque or some otherocclusive material 14 (FIG. 2) within the interior of the graft.

[0047] The atherectomy catheter 22 is introduced into the patient'svascular system in a conventional manner, e.g., via the use of theintroducer sheath and guide catheter. As shown, this is accomplished viaa percutaneous puncture 16 in the femoral artery 18. The sheath 26 andguide catheter 24 are each of conventional construction and thus theirdetails will not be described in the interest of brevity.

[0048] The working head 32 is arranged to rotate about the longitudinalaxis of the catheter at a high rate of speed, e.g., from 10,000 rpm to200,000 rpm to repeatedly mechanically impact the occlusive material. Atthe same time, an infusate liquid (to be described later) is pumpedthrough the atherectomy catheter by a pump (to be described later andforming a portion of the debris removal sub-system 30) and out of distalend of the atherectomy catheter adjacent the working head. The openingof the occlusion to allow freer flow of blood therethrough is effectedby impacting surfaces of the rotating working head impacting theocclusive material 14, whereupon portions thereof are removed, e.g.,broken away. In addition, as will be described later, the rotation ofthe working head produces a powerful, toroidal shaped vortex contiguouswith the working head. This vortex flow has the effect of recirculatingparticles that are broken off from the occlusive material by the impactof the rotary working head's impacting surfaces back into contact withsuch surfaces. Accordingly, those particles are repeatedly impacted,with each impaction reducing the size of the particles further until themajority of resulting particle sizes are very small, e.g., less than 200microns. At the same time another pump (also to be described later) ofthe debris removal sub-system 30 is operated to aspirate the particlesproduced during the revascularization procedure along with the infusateliquid and some blood.

[0049] Thus, as will be described in detail later, the debris removalsubsystem 30 utilizing a downstream balloon, as will be described later,is operative to ensure that debris produced as the working head opens alumen through the occlusion is not able to flow upstream into theupstream vessel, e.g., the aorta 12, during the lumen opening procedure,and once the working head breaks through or exits the occlusion on thedownstream side, that the debris is not able to flow downstream into thedownstream blood vessel(s).

[0050] As best seen in FIG. 4 the atherectomy catheter includes a jacket34 which is formed of any suitable material, e.g., plastic, and has asmall outside diameter. In the preferred embodiment shown herein, theoutside diameter of the jacket 34 is approximately 1.5 mm (5 French).This size catheter is merely exemplary. The means for effecting therotation of the working head is the heretofore identified drivesub-system 28. That sub-system is similar to the drives disclosed in theaforementioned U.S. Pat. Nos. 4,686,982, and 4,747,821 and basicallycomprises an air-turbine motor and associated rotary drive cable (to bedescribed later). Other drive systems can be utilized, as well.

[0051] Irrespective of the construction of the drive system, it iscoupled to the working head 32 so that the working head is rotated aboutits longitudinal axis at the high rate of speed. Many of the details ofthe working head will be described later. Suffice it for now to say thatthe working head 32 includes an impeller portion 44 and a central shankportion or axle 36 (FIG. 4) projecting proximally therefrom. The axle 36is supported in a central bore of a bushing 38 fixedly mounted at thedistal end of the catheter's jacket 34 by an encircling mounting band40. The shank 36 is fixedly secured to the distal end of a flexibledrive cable 42 forming a portion of the drive sub-system 28.

[0052] The impeller 44 forms the distal portion of the working head andis fixedly secured to the shank 36 so that it will be rotated at a highrate of speed about its longitudinal axis by the concomitant rotation ofthe drive cable. The impeller portion 44 comprises a circular disk orbase 52 from which a generally planar tip 54 projects. The tip 54 has apair of generally planar diametrically disposed relieved side surfacesor faces which merge with an arcuate front or distal surface to form apair of arcuate impacting surfaces 54A and 54B. Each of the impactingsurfaces is radiused in a plane perpendicular to the axis of rotation ofthe working head so that each is not sharp, e.g., is in the range ofapproximately 0.001 inch to approximately 0.008 inch, although in thescale of the figures of the drawing they appear to be a sharp line. Theworking head is located within a cylindrical shroud 56 (FIGS. 3 and 4)fixedly mounted on the front of the bushing 38. The shroud 56 includes acylindrical sidewall portion 58 and a generally conical distal wallportion 60 terminating in a circular opening 62 in the distal endthereof. The shroud may be of any suitable outside diameter, e.g., 7 to8 French. The distal arcuate portion of the impeller tip 54 projects outof the central or front opening 62. A side port or open window 64 islocated in the sidewall 58.

[0053] As mentioned earlier the system 20 utilizes an infusate liquid toexpedite the revascularization of the vessel. In particular, theinfusate liquid is pumped at a flow rate Q₁ (to be described later) downthrough the interior of the catheter jacket 34 through fourequidistantly spaced grooves 46 extending down the central bore of thebushing 38 and via radial ports 48 to an annular recess 50 in the frontwall of the bushing. The annular recess is in fluid communication withthe side port or window 64 in the shroud so that the infusate liquid canexit therefrom. The direction of flow of the infusate liquid down theatherectomy catheter and out the shroud at its working head is shownclearly in FIG. 4.

[0054] The rotation of the working head about its longitudinal axisproduces a powerful toroidal shaped vortex flow Q₃ in the fluidcontiguous with the working head. This flow Q₃ circulates by enteringinto the shroud through the central or front opening 62 and exits outthrough the side window 64 as shown in FIG. 3. Thus, the flow exitingthrough window 64 is Q₁ +Q₃. As will be appreciated by those skilled inthe art the vortex flow Q₃ has the effect of recirculating any particlesthat are broken off from the occlusive material 14 by the action of therotating working head back into contact with the working head'simpacting surfaces. Thus, the occlusive material particles which arebroken away are progressively reduced in size until they are aspiratedby aspiration means forming a portion of the debris removal sub-system30. That means will be described later. Suffice it for now to state thatthe aspiration means withdraws the infusate liquid, the debris particlesand some blood at an aspiration flow rate of Q₂.

[0055] As should be appreciated by those skilled in the art the liquidexiting from the window 64 of the shroud will tend to push theatherectomy catheter's distal end sideways or laterally in the directionopposite to the direction of the liquid exiting that window. Thishydrodynamic action may be used to aid in steering the catheter to adesired position with respect to an occlusion to be revascularized. Inthis regard, for example, when negotiating a branch in the artery systemto reach the occlusion to be revascularized, the atherectomy cathetercan be rotated or twisted about its longitudinal axis so that theshroud's window is facing in the opposite direction to the branch to beentered. This action will cause the side directed liquid exiting thewindow 64 to push the catheter's distal end sideways, whereupon it canenter the desired arterial branch. Such “hydrodynamic steering” of theatherectomy catheter can be accomplished in other manners and by othermeans than by the use of a shroud having a single side window or port.Thus, this invention contemplates an intravascular catheter instrument,of any type, including any means for producing an asymmetric, e.g., sidedirected, fluid flow adjacent the distal end of the catheter so that itcan be steered into a desired position by appropriate rotation of thecatheter about its longitudinal axis.

[0056] As mentioned earlier, the guide catheter 24 is of anyconventional construction. In the preferred embodiment shown in FIG. 1it is a 10F to 12F catheter having a conventional Y connector 66 at itsproximal end. The Y connector 66 has one input leg including aTouhy-Borst adjustable hemostasis valve 66A through which theatherectomy catheter 22 passes. The other input leg, i.e., the angledleg 68, is connected to the aspiration portion of the debris removalsub-system 30 (to be described later).

[0057] Power for operating the atherectomy catheter is provided by thedrive sub-system 28. That system includes an air turbine motor 70 whichis coupled to the proximal end of the flexible drive cable 42. The airturbine 70 is provided with compressed air via an input line or conduit72. Air for the line 72 is provided from a source (not shown) via anassociated regulator 74, and the conventional control valve 76. Thecontrol valve is coupled to the input line 72 of the air turbine. Apressure gauge 78 is connected between the regulator 74 and the controlvalve 76. The regulator 74, the control valve 76, the pressure gauge 78and the associated lines or conduits and the air source make up thedrive sub-system 28. The control valve 76 is of any conventionalconstruction, be it mechanical or electrical. The air turbine motor 70is also of any conventional construction, as is the regulator 74 and thepressure gauge 78. The air turbine includes an outlet port incommunication with the ambient atmosphere, via a line 80. It must bepointed out at this juncture that the atherectomy catheter 22 need notutilize an air turbine motor to rotate the working head. For example, anelectric motor can be provided to replace the air turbine to drive therotating cable and the associated working head.

[0058] The debris removal sub-system 30 basically comprises a source 82of the infusate liquid “S”, e.g., saline plus a 30% contrast media, afirst positive displacement pump 84, an input line or conduit 86, anoutlet line or conduit 88, a second positive displacement pump 90, and adebris collection vessel 92. The input line 86 and its associatedcomponents, i.e., the pump 84 and infusate source 82 serve as the“infusion” means for the system 20. To that end the input line 86 iscoupled via a connector to the interior of the atherectomy catheter,i.e., to the annular space within the catheter's jacket between it andthe drive cable. The infusate liquid S is pumped at the flow rate Q₁ bythe positive displacement pump 84 through line 86 from the supply orsource 82. Thus, the infusate liquid S exits the catheter's working headand circulates as described earlier.

[0059] The rate of flow Q₁ of the infusate liquid is established by thepositive displacement pump 84 under control of some automatic or manualcontroller (not shown). In accordance with one exemplary method of usethe pump is operated to produce a flow rate Q₁ the range of 5-80 ml. perminute.

[0060] The output line 88 and its associated components, i.e., the pump90 and debris collector vessel 92 serve as the “aspirating” means forthe debris removal sub-system 30. To that end, the aspiration line 88 isconnected to the leg 68 of the Y connector 66. The pump 90 is arrangedto be operated to pump the infusate liquid, the debris produced by therevascularization, and some small amount of blood at the flow rate Q₂ inthe proximal direction through the annular space between the atherectomycatheter 22 and the guide catheter 24 and out through the connector leg68 into the outlet line 88, and from there to the collector vessel 92.

[0061] The flow rate Q₂ is selected to be greater than Q₁. For example,in one exemplary method of use the flow rate is selected to be in therange of 5-100 ml. per minute, with the differential between Q₂ and Q₁being between 5 and 50 percent. The use of an aspiration flow rate Q₂which is higher than the infusion flow rate Q₁ insures that any debris,e.g., particles of the occlusive material making up the graft's lesion,produced from debriding that material is positively prevented fromflowing into adjacent vessel portions. In this regard, as will beappreciated by those skilled in the art, since the aspiration flow rateQ₂ is greater than the infusion flow rate Q₁, some blood equal to Q₂-Q₁will also be withdrawn from the upstream vessel, e.g., the aorta asshown in FIGS. 1 and 3. The withdrawal of some blood from that vesselinsures that the debris produced cannot flow upstream to enter into it.Instead the debris particles will be entrained within the infusateliquid and blood which is withdrawn through the aspiration line. Therate of blood withdrawn is preferably be kept to a minimum, e.g., 40 ml.per minute in the interests of patient safety.

[0062] In accordance with a preferred aspect of this invention theoperation of the pumps 84 and 90 are coordinated so that Q₂ is equal tosome variable times Q₁, where that variable is greater than 1 and isadjustable to accommodate the needs of the patient. Moreover, thecoordination of the flow rates is preferably accomplished automatically,so that a change in one flow rate automatically results in aproportional change in the other flow rate. This coordinated action maybe accomplished by a mechanical linkage between the pumps, or by acommon electrical controller for the pumps. Manual control of the pumpsis also envisioned for some applications.

[0063] In any case, any suitable positive displacement pumps can beutilized, e.g., peristaltic pumps or piston pumps, in the system.

[0064] In order to expedite the revascularization of the bypass graft,the infusate liquid may be provided with a contrast medium, e.g., 30%contrast medium, so that the revascularization procedure can be viewedusing conventional imaging techniques. Moreover, the infusate liquidcan, if desired, be oxygenated to eliminate distal ischemia when thecatheter is used for arterial restriction opening procedures. Also, ifdesired, small amounts of heparin, urokinase, etc., or other drugs canbe added to the infusate liquid for the procedure.

[0065] As should be appreciated from the foregoing the subject inventionprovides a viable means for effecting the revascularization of partiallyor totally occluded coronary bypass grafts, while assuring that anydebris particles produced during the revascularization procedure isremoved from the patient's body. In addition, the subject invention issuitable for revascularizing other occluded vessels, as well. Forexample, in FIG. 5 the system is shown in use revascularizing a totallyoccluded femoral artery 18 downstream of the profunda femoris 18A. Inthis application the system functions to capture the debris createdduring the lumen opening procedure by preventing it from going alongside the catheter and exiting down the profunda to end up in the distalcapillary beds. In this application, a portion Q₄+Q₁-Q₂ of the bloodflowing down the femoral artery 18 to the situs of the occlusion will bepermitted to flow into the profunda femoris, while the portion Q₂-Q₁ ofthe blood and infusate liquid is diverted and/or withdrawn into theguide catheter to ensure positive debris removal in the same manner asdescribed earlier. For some persons, e.g., diabetics with severelycompromised distal capillary beds, a femoral artery revascularizationprocedure is likely to prove beneficial.

[0066] Turning now to FIGS. 6A and 6B, an alternative embodiment 100 ofthe system of the subject invention is shown. The system 100 is similarin most respects to system 20 described heretofore. One majordifference, however, is that the atherectomy catheter is arranged foruse over a guide wire (to be described later). The guide wire includes adebris blocking member, e.g., an inflatable balloon (also to bedescribed later). When the atherectomy catheter is in place on the guidewire the balloon is located distally of the working head of theatherectomy catheter and the balloon serves to physically block anydebris produced by the system 100 which may tend to escape extractionfrom flowing distally. The atherectomy catheter used in the system 100is designated by the reference numeral 22′ and is identical in mostrespects to the catheter 22 described heretofore. In the interests ofbrevity, the features common to catheters 22 and 22′ will not bereiterated. So too, the features common to systems 100 and 20 will alsonot be reiterated. Moreover, in the interests of drawing simplicitycommon components will be given the same reference numerals.

[0067] As can be seen in FIGS. 6A and 6B, the system 100 includes acontroller or console 102 housing the heretofore identified infusatepump 84 and the extraction pump 90. Each of these pumps is a peristalticpump. The console 102 also includes a flow control section 104 forestablishing the various fluid flows of the system, as will be describedlater, and a speed control section 106 for establishing the operationalspeed of the working head of the atherectomy catheter. The details ofthe speed control section 106 will also be described later. A perfusatepump 108 is also provided in the console 102. The perfusate pump 108 isalso a peristaltic pump and its operation will be described later.Suffice it for now to state that the pump 108 is arranged to provide aperfusion liquid, e.g., blood or a suitable synthetic oxygenationliquid, downstream of the inflatable balloon to perfuse downstream(distally) located tissue. The pump 108 also serves to effect theinflation of the balloon.

[0068] Compressed gas (e.g., air or nitrogen) is provided via line 72from the console 102 to the catheter's turbine 70. The console, in turn,receives the compressed gas from a tank 110 via an input line 112. Therotational speed of the turbine is controlled by the speed controlsection 106 of the console 102. On/off operation of the turbine iscontrolled by a turbine foot control pedal 114 and an associated gasline 116 connected to the console. This pedal also initiates operationof the infusate pump 84.

[0069] The speed control section 106 of the console includes a rotaryknob for establishing the desired rotational speed of the turbine and anassociated digital display for displaying the turbine's speed. Theconsole also includes an on/off switch 118 for enabling electrical powerto be provided to the system's electrical components when the switch isin the “on” position.

[0070] The foot pedal 114 is used by the operator of the system 100 toinitiate operation of the infusate pump to cause the infusation liquidto flow down the guide wire and out its distal end and to start theatherectomy catheter's turbine 70 a short time, e.g., 2 seconds, afterthe infusate liquid begins to flow. The use of the foot pedal frees theoperator's hands for other purposes.

[0071] The perfusate pump 108 is connected via an input line to a bag120 containing the perfusion liquid. The output of the perfusate pump108 is provided via a line 122 to the guide wire of the system 100. Theguide wire is designated by the reference numeral 124 and includes theheretofore identified balloon. That balloon is designated by thereference number 126 and, as seen clearly in FIGS. 6B, 7 and 8, islocated adjacent the distal end of the guide wire 124.

[0072] The atherectomy catheter 22′ is an “over-the-wire” type ofdevice. Thus, it includes a central lumen for receipt of the guide wire124 so that the catheter 22′ can be threaded over the guide wire 124.The guide wire 124 serves to perfuse distally located tissue and toinflate its balloon 126 so that the balloon blocks any particulatematerial (debris) from flowing distally. To accomplish these functions,the perfusate liquid in the bag 120 is pumped by the perfusate pump 108through the line 122 and through the interior of the guide catheter 124where some of it fills or inflates the balloon and the remainder exitsat the distal end of the catheter to perfuse downstream tissue, as willbe described later.

[0073] The rate of flow of the infusate, extraction and perfusateliquids is established by the flow control section 104 of the consolevia its various up/down switches and associated digital displays. Asdiscussed earlier, the ratio of the infusate flow rate to the extractionflow rate is adjustable. This is accomplished by the appropriate settingof the “infusate flow” and “ratio” up/down switches of the flow controlsection of the console. The desired ratio and the infusate flow rate aredisplayed by the associated digital displays.

[0074] In FIG. 7 there is shown in greater detail the distal end of theatherectomy catheter 22′ located within a diseased bypass graft, e.g., are-occluded mammary artery 10′. The diseased artery leads to a distalblood vessel 15, i.e., the vessel to be fed by the graft 10′. The guidewire 124 is in the form of an elongated flexible member, whoseconstruction will be described later with reference to FIG. 8. Thedistal end of the guide wire 124 is in the form of a somewhat soft orflexible, precurved tip 128. The free end of the catheter's tip is ahemispherical dome 130. The balloon 126 is disposed slightly proximallyof the free end 130 of the guide wire 124.

[0075] In FIG. 8 the details of the distal end of the guide wire 124 andballoon are shown (although the tip 128 is shown being linear in theinterest of drawing simplicity). Most of the length of the guide wire,i.e, from its proximal end to the location of the balloon 126, is in theform of a two start helical spring 132 (see FIG. 8) whose convolutionsare in close engagement (abutment) with one another. The spring 132enables the guide wire to be bent through a small radius of curvature tofacilitate its intravascular placement via the conventional guidecatheter 24. Inside the helical spring 132 is a liquid impervious, e.g.,rubber or plastic, flexible liner tube 134. This tube prevents theegress of the perfusate liquid through the interface between successiveconvolutions of the helical spring 132 as that liquid is pumped down theguide wire 124.

[0076] A perforated support tube 136 is mounted within a distal endhelix termination 138 of the spring 132. The support tube 136 isarranged to mount the balloon 126 thereon and includes a plurality ofradially located apertures or ports 140. The balloon 136 is an annularmember of any conventional construction, e.g., rubber, and is mounted onand is disposed about opposite ends of the perforated support tube 136.In particular, the balloon 136 is held in place and sealed to theperiphery of the support tube at each end thereof via respective bands142. Each band 142 extends about one cylindrical end of the balloon.Thus, when the perfusion liquid is pumped down the guide wire 124 by thepump 108 it passes through the apertures or ports 140 (as shown by thearrows in FIG. 8) to fill up, i.e., inflate, the balloon 126.

[0077] The distal end of the perforated support tube is located within aspring helix termination 144 forming the proximal end of the guide wiretip portion 128. The portion 128 is also formed as a two start helix,like portion 132. However, no fluid-impervious sleeve is located withinthe tip portion 128 so that the interface between successiveconvolutions of the spring forming the tip portion 128 serve aspassageways through which the portion of the perfusion liquid whichdoesn't enter the balloon exits the guide wire as shown by the arrows146 in FIG. 8.

[0078] Since the atherectomy catheter 22′ is designed for over-the-wireuse, the drive cable for rotating its working head is in the form of aspiral spring helix having a central lumen extending down its center.The proximal end of the drive cable is connected to the output of theturbine 70 while the distal end is connected to the working head. Thatworking head is designated by the reference number 32′ and is shown inFIGS. 6A and 7. The central lumen of the spiral helix drive cable formsthe passageway for receipt of the guide wire 124. If desired ananti-friction sleeve or some other anti-friction bearing can be providedat the interface between the inner surface of the spiral drive cable andthe outer surface of the guide wire. The working head 32′ is similar inconstruction to the working head 32 of system 20 except that the workinghead 32′ includes a central bore 148 through which the guide wire 124extends. As can be seen clearly in FIG. 7, the working head 32′ isunshrouded, i.e., is not located within a shroud like the working head32 of the atherectomy catheter 22.

[0079] Operation of the system 100 is as follows:

[0080] The guide wire 124 with its balloon 126 deflated and with theatherectomy catheter 22′ mounted thereon so that the balloon 126 and tipportion 128 extend beyond the working head 32′ is threaded through apreplaced guide catheter 24 in the patient's vascular system until it isat a desired situs, such as at the arch of the aorta. At this point theguide wire 124 is advanced with respect to the atherectomy catheter 22′so that the guide catheter crosses the lesion or atheroscleroticdeposits in the bypass graft 10′. The precurved tip of the guide wire124 facilitates the placement of the guide wire. In this regard, theguide wire can be rotated about its longitudinal axis to point the tip130 in the desired direction.

[0081] Once the guide wire 124 is at the desired position, such as shownin FIG. 7, the balloon 126 can be inflated and the distally locatedtissue perfused. The exiting perfusion liquid is shown by the arrows inFIG. 7. In particular, the perfusate liquid is pumped by pump 108 andassociated conduit 122 through the hollow interior of the guide wire124, so that it passes through the apertures or ports 140 in the supporttube 136 to inflate the balloon 126 to the state shown in FIG. 7, whilethe remainder of that liquid flows out of the open distal end of thesupport tube 136, into the hollow interior of guide wire's tip 128, andout through the interface between the immediately adjacent convolutionsof the tip. Accordingly, distally located tissue is oxygenated,notwithstanding the fact that the balloon is inflated and thus blockingthe flow of blood through the bypass graft 10′.

[0082] If no perfusion or oxygenation of distally located tissue isdesired, the system may utilize an alternative guide-wire mounteddebris-blocking balloon. That alternative embodiment of the guide-wireis designated by the reference number 124′, is shown clearly in FIG. 14,and will be described in detail later.

[0083] The rate of flow of the infusate liquid is set by the flowcontrol section switch and the ratio of that flow to the extraction flowrate is established by the ratio control switch of the flow controlsection. Accordingly, when ready the operator presses the foot pedal 114to start the infusate pump. This action provides the infusate liquidthrough line 86 and through the associated components of the catheter22′, whereupon the infusate liquid exits from the catheter at theworking tip 32′ as described earlier. The rate of extraction of liquidthrough the annular space between the inner surface of the guidecatheter 24 and the outer surface of the atherectomy catheter 22′ isestablished by the extraction pump 90 under control of the associatedflow controls of the console. The turbine 70 is arranged to commenceoperation on a fixed time delay, e.g., 2 seconds, after the infusatepump commences operation in response to the depression of the foot pedal114. This action causes the working head to begin rotating at a highrate of speed. The desired speed setting for the turbine is establishedby setting of the rotary knob of the speed control section of theconsole. Preferably some restraining means (not shown but like thecradle assembly of the system 200 to be described later) is used to holdor clamp the guide wire in position when the atherectomy catheter isoperated to prevent the rotation of the working head 32′ from causingthe guide wire to rotate. The compressed gas e.g., nitrogen or air,powering the turbine 70 of the atherectomy catheter 22′ vents to theatmosphere via line 80. The debris particles produced by the rotaryworking head repeatedly impacting the plaque or other deposit within thediseased graft are withdrawn by the extraction pumps into the collectionbag 92, in the same manner as discussed earlier. Any debris particleswhich may have otherwise escaped being withdrawn from the patient's bodyby the extraction subsystem are positively prevented from flowingdistally by the barrier established by the inflated balloon 126. Thus,such particles will eventually be extracted. After the diseased bypassgraft has been opened, the balloon 136 can be deflated by turning offthe infusation pump. Then, the atherectomy catheter 22′ and the guidewire 124 can be removed through the guide catheter 24.

[0084] It must be reiterated that the atherectomy catheter for producingthe lumen through the vascular occlusion need not be a rotary impactingdevice, like described above. Thus, a system constructed in accordancewith any embodiment of this invention may make use of any instrumenthaving any type of working head, e.g., a reciprocating impacting workinghead, a combined rotary and reciprocating impacting working head, arotary cutting head, a reciprocating cutting head, a rotary abrasivehead, etc., to open the lumen in the occlusive material in the bloodvessel. Moreover, the working head need not be shrouded. In fact, any ofthe heretofore identified prior art atherectomy devices can be utilizedas part of the system 20 or 100. Some thrombectomy devices may also beutilized as part of the system 20 or 100 (or even as part of the systems200 and 500, to be described later). One such potential device is theAmplatz Thrombectomy Device designated by the trademark CLOT BUSTER byMicrovena Corporation. It should also be pointed out that the workinghead of the device for forming the lumen need not even engage theocclusive material, so long as its lumen-opening operation producesdebris particles to be removed. Thus, devices making use of liquid jets,laser beams, etc., can be utilized to open the lumen as part of thesystem of this invention. In short, any type of instrument for opening alumen through the occlusive material and which produces debris canbenefit from use in the system of this invention, i.e., a system whichestablishes a differential flow, wherein the infusate flow is less thanthe aspiration flow so that particles or pieces of occlusive materialremoved are positively precluded from flowing into adjacent vessels.Moreover, while the production of a local vortex flow adjacent theworking head is desirable to effectuate the lumen opening process and toreduce debris particle size, it is not crucial to this invention.

[0085] In the embodiments described in FIGS. 1-8, it has been assumedthat there will be some blood flow from the patent upstream bloodvessel, e.g., the aorta in the case of a revascularization of a bypassgraft, which may flow about the exterior of the distal end of the guidecatheter 24 to merge with the flow being drawn into the passagewaybetween the guide catheter 24 and the atherectomy catheter 22. See forexample, FIG. 7 wherein blood flow Q₂-Q₁ from the aorta flows around theouter surface of the distal end of the guide catheter 24 between theguide catheter and the inner wall of the bypass graft 10′. In the eventthat blood flow from the upstream, patent artery, e.g., the aorta 12, isprecluded from entering the guide catheter 24, such as by the outerperipheral surface of the distal end of the guide catheter 24 tightlyengaging the inner periphery of the bypass graft 10′ to berevascularized, care must be taken to control the ingress and egressflow rates with respect to each other to ensure that the bypass graftdoes not collapse since the extraction or aspiration rate will exceedthe infusion rate. As will be appreciated by those skilled in the art,if the bypass graft does collapse, the rotating working head 32 will beforced against the inner surface of the bypass graft wall, which is nowin a flatulent state, and the risk of vascular damage will increase.

[0086] In prior art devices, such as the Clement et al. U.S. Pat. No.5,681,336 the potential for vessel collapse is even more acute. In thisregard, the Clement et al. patent positively seals off a space in thevessel to be revascularized between a pair of balloons. In particular,one balloon is located on the distal end of a guide wire distally of therestriction to be opened and the other balloon is located on the distalend of a guide catheter through which a rotary ablation catheterextends. Thus, when suction is applied to that space to evacuate theparticles produced by the revascularization process, if the extractionrate is not precisely controlled and coordinated to the infusion rate,vessel collapse may occur to bring the vessel wall into the rotatingburr.

[0087] The subject invention overcomes this potential vascular collapseproblem. In particular, in FIGS. 9-13 there is shown another alternativeembodiment of a system 200 constructed in accordance with this inventionutilizing an atherectomy catheter 22″ for revascularizing occludedvessels, e.g., coronary bypass grafts. The system 200 obviates theproblem of potential vessel collapse by providing automatic access toblood flow from a patent, upstream vessel, e.g., the aorta 12, via useof at least one flow control or regulation port in the wall of the guidecatheter 24 (or any other tubular member through which the atherectomycatheter 22″ extends and through which the infusate liquid, blood anddebris will be aspirated). The flow control or regulation port(s)extend(s) through the wall of the guide catheter 24 close to its distalend, yet is(are) located sufficient proximally from the distal end ofthe guide catheter so that when the guide catheter is in its normalposition for enabling an atherectomy catheter 22″ (to be describedlater) to revascularize the restricted vessel, e.g., a coronary bypassgraft 10′, the side port(s) is(are) in direct fluid communication withthe blood flowing in the patent upstream vessel, e.g., the aorta 12. Inthe exemplary embodiment of the system 200 shown in FIGS. 9-13 two suchside flow regulation ports 24A and 24B are provided near the distal endof the guide catheter 24. As will become apparent later the size,location and number of flow regulation side ports used is a matter ofchoice, depending upon various system parameters. For example, for asystem making use of a guide catheter of 9 French (one suitable size foreffecting the revascularization of coronary bypass grafts), two sideports 24A and 24B, each of 0.032 inch, may be used. Alternatively, onlyone side port 24A of 0.04 inch may be used. Other number(s) and sizes ofside port(s) can be used as well.

[0088] Since the two side ports 24A and 24B extend through the wall ofthe guide catheter 24, they are in fluid communication with the interiorof the guide catheter, and hence with the annular space or passagewaybetween the inner surface of the guide catheter 24 and the outer surfaceof the atherectomy catheter 22″ which extends through the guidecatheter. As described earlier it is through this annular space orpassageway that the infusate liquid, blood and any debris, e.g.,atherosclerotic plaque produced by the revascularization procedure, isextracted by the extraction subsystem.

[0089] The use of at least one flow regulation or control port ensuresthat the vessel being revascularized does not collapse as the debris isextracted, even if the guide catheter 24 is tightly fit within thebypass graft 10, such as shown in FIG. 10, and even if the extractionpump 90 is operating at a much higher rate that the infusate pump 84.This automatic control or regulation provided by the at least one sideport(s) will be described after a brief background discussion. To thatend, as will be appreciated by those skilled in the art, if the guidecatheter 24 (or other tubular member through which the atherectomycatheter extends) does not tightly fit in the bypass graft (such asshown in FIG. 11), blood from within the aorta 12 may flow around theoutside of the guide catheter 24 (see the arrows A1) to join with theblood, debris particles and infusate fluid flowing into the open end ofthe guide catheter (see the arrows A2). Accordingly, the action of theextraction pump to remove liquid from the space in the bypass graftsection between the end of the guide tube and the distally locatedblocking balloon 126′ (forming a portion of the guide-wire 124′ to bedescribed later), will not collapse that vessel section, even if theguide catheter does not make use of any flow control or regulation sideport(s). If however, a guide catheter without any flow control orregulation side ports is tightly fit within the bypass graft, thepossibility for vessel collapse exists if the extraction rate is notcontrolled precisely with respect to the infusion rate as discussedearlier.

[0090] By utilizing at least one flow control or regulation side portthis potential hazard can be eliminated since such port(s) will provideautomatic access to blood flow in the upstream, patent vessel. In thisregard, as can be seen in FIG. 10, with the guide catheter 24 in placetightly engaging the periphery of the bypass graft section 10′ bloodfrom the aorta 12 is enabled to flow into the flow control regulationports 24A and 24B as shown by the arrows A1. This blood then merges withthe flow (shown by arrows A2) of blood, infusion liquid and debrisparticles produced by the action of the rotary working head 32″ in thebypass graft section between the distally located blocking balloon 126′of the guide wire 124′ (a variant of guide-wire 124 and which will bedescribed later with reference to FIG. 14) and the distal end of theguide catheter 24. By appropriate sizing of the flow control sideport(s) one can ensure that the pressure within the vessel beingrevascularized, e.g., the bypass graft, is positive, thus ensuring thatthe vessel section will not collapse.

[0091] The foregoing automatic flow control feature of this inventionrenders it useful with other revascularization systems than those of thesystems disclosed herein. For example, a guide catheter 24 having atleast one flow control port (or any other tubular member through whichan atherectomy catheter is extended) can be used with any prior artatherectomy catheter system, e.g., the atherectomy system of theheretofore identified Clement et al. U.S. Pat. No. 5,681,336.

[0092] As discussed previously, it is desirable to operate theextraction pump at a rate to pull more fluid out of the vessel sectionbeing revascularized than the rate at which infusion liquid isintroduced by the infusion pump to ensure that debris is removed even.By the use of a guide catheter 24 having at least one flow regulationport, like that described above, one can accept a significant mismatchin flow between the infusate flow and the extraction flow and still notrisk collapse of the vessel being revascularized. This factorconsiderably simplifies the amount of coordination between theextraction pump and the infusion pump.

[0093] As mentioned earlier the size of the port or ports is a functionof various system parameters. In particular, it may be calculated usingthe following mathematical formulae.

[0094] Pressure loss (P2-P3) through the space between the guidecatheter and the working catheter is viscous and is given by thefollowing “Equation (1)”:$\left( {{P2} - {P3}} \right) = \frac{\left( {{Q1} + {Q2} + {Q3}} \right) \cdot L \cdot \mu \cdot e}{1.81 \cdot 10^{6} \cdot {D\left( \frac{\left( {{D1} - {D2}} \right)}{2} \right)}^{3}}$

[0095] Where:

[0096] Q1+Q2+Q3=flow in³/sec;

[0097] D1=Guide catheter inner diameter (inches);

[0098] D2=Working catheter outer diameter (inches);

[0099] L=Guide catheter length (inches);

[0100] P2=vessel pressure (psi);

[0101] P3=vacuum source pressure (psi);

[0102] e=eccentricity factor, D1 rel. to D2.

[0103] Thus, for example, if:

[0104] L=41 inches;

[0105] D1=0.098 inches;

[0106] D2=0.067 inches μ=3.25 centipoise e=1.5 if D1 touches D2.

[0107] Then Equation (1) becomes$\left( {{P2} - {P3}} \right) = {\frac{\left( {{Q1} + {Q2} + {Q3}} \right)}{7.31}\left( {{{if}\quad {Q1}},{Q2},{{Q3}\quad {{mL}/\min}},{{{P2}\&}{P3}\quad {in}\quad {{psi}.}}} \right)}$

[0108] The pressure loss through the bypass port(s) has non linearrelationship to flow as set forth in the following “Equation (2)”:

Q2=90,950.0·Ab·(P1−P2)^(0.5)

[0109] Where

[0110] Q2=flow mL/min

[0111] Ab=bypass port area in²

[0112] P1=aorta (or upstream patent vessel) pressure psi.

[0113] P2=vessel pressure psi.

[0114] Equations (1) and (2) assume that there is a tight fit betweenthe outer surface at the distal end of the guide catheter 24 (so thatblood from the upstream, patent vessel cannot flow past the distal endof the guide catheter, as is the case shown in FIG. 7) and the totalflow of blood, infusion liquid, and debris into the open end of theguide catheter is very low. Moreover, the calculations for the size ofthe control or regulation port(s) which follow is based on theassumption that the extraction pump 90 is not satisfied for flow andtherefore has sucked or evacuated down to its limit of 27 inches ofmercury, whereupon it functions as a vacuum source, rather than a flowsource.

[0115] Equations (1) and (2) can best be solved graphically. To thatend, the graph in FIG. 15 shows the solutions to pressure and flow forseveral sizes of flow regulation port(s) and for the guide catheter 24using Equations (1) and (2). The intersection of the curves for the twoequations represents the solution to those equations. Thus, it will beseen from the graph that the solutions for the equations with a guidecatheter 24 having a pair of side ports 24A and 24B, each of 0.032 inchdiameter, or a single side port 24A of 0.040 inch diameter, result inpositive pressures, i.e., pressure above venous pressure. Consequentlythe portion of the restricted vessel, i.e., bypass graft section 10′,between the distal balloon 136 and distal end of the guide catheter 24will not collapse. However, where only one side hole or port is used andthat port is either 0.032 inch diameter or of 0.025 inch diameter, anegative pressure will result in the bypass graft section 10′, so thatthe vessel section could collapse.

[0116] It must be pointed out at this juncture that the foregoingexamples are only a few of many that are possible to provide automaticprotection against vessel collapse utilizing any number of side ports ofvarious dimensions. Other factors which may be considered in the choiceof number, shape and location of the at least one side port, are thedesired structural integrity of the distal end of the guide catheter atthe location of the side port(s), and the possibility of side portblockage by a portion of the wall of the patent upstream vessel or thewall of the vessel section being revascularized.

[0117] In FIGS. 9A, 9B, 12 and 13 there are shown the details of system200. That system basically comprises the same system as the system 100shown in FIGS. 6-8 described heretofore, with some slight minormodifications (as will be described later). Thus, in the interest ofbrevity, the common components of those systems will be given the samereference numbers and their construction and operation will not bereiterated.

[0118] The system 200 basically comprises a guide catheter 24, amodified guide wire 124′ with a distally located inflatable balloon 126,an atherectomy catheter 22″ with a distally located rotary working head32″ disposed over the guide wire and within the guide catheter to bemoved longitudinally with respect thereto, a drive sub-system 28 forrotating the working head 32″, a cradle assembly 202 (FIG. 9A) forsupporting the turbine and associated portion of the drive sub-system,for fixing the position of the guide wire 124 and guide catheter 24 andfor enabling the atherectomy catheter 22″ to be moved longitudinallywith respect to the guide catheter and the guide wire, a source 110 ofcompressed gas, e.g., nitrogen or air, to power the drive sub-system, adebris removal sub-system 30 made up of an extraction pump 90 andassociated components, and a control console 204.

[0119] The guide wire 124′ is shown clearly in FIG. 14 and is similar tothe guide wire 124 in that it includes an inflatable balloon 126′located immediately adjacent the distal end of the guide wire 124′, aflexible distal end portion 128′ immediately distally of the balloon126′ and terminating in an atraumatic tip 130′ at the distal end of theguide-wire 124′. However, the guide wire 124′ is not arranged to perfusedownstream tissue, as is the case of the guide wire 124. Thus, as can beseen in Fin 14 the guide wire 124′ basically comprises an elongatedsmall diameter, flexible, hollow wire or tube 180, e.g., a “hypo” tubeformed of type 304 stainless steel having a 0.010 inch outside diameterand a 0.005 inch inside diameter. A central passageway or bore 180Aextends the full length of the guide-wire tube 180.

[0120] The balloon 126′ is formed of any suitable material, e.g., latexof a thickness of approximately 0.006 inch, and is fixedly securedslightly proximally of the distal end portion of the tube 180 via aplurality of loops or lashes of a filament 182, e.g, polypropylene,wrapped about the tubular proximal end portion 184 of the balloon 126′and similar loops or lashes 182 wrapped about the tubular distal endportion 186 of the balloon 126′. This creates a confined space withinthe balloon and into which an inflation gas, e.g., carbon dioxide, is tobe provided via the guide-wire tube 180 to inflate the balloon. To thatend plural gas ports 180B extend through the wall of the guide-wire tube180 in communication with the interior of the balloon and with thecentral passageway 180A in the guide-wire tube 180. The balloon can beany suitable size, depending upon the application. For example, forrevascularizing a typical bypass graft, the outside diameter of theballoon when deflated may be approximately 0.03 inch, and may beinflated to an outside diameter of up to 0.2 inch (5 mm).

[0121] A tapered, flexible, core wire 188, e.g., type 304 stainlesssteel, is soldered by any suitable lead-free solder into the distal endof the central passageway 180A of the guide-wire tube 180 to seal itsdistal end. A tight helix or coil 128′ is also soldered by a lead-freesolder to the outer surface of the distal end of the tube 180. The coil128′ forms the curved, flexible distal end of the guide-wire and can befabricated of any suitable radiopaque material, e.g., platinum wire of0.003 inch diameter. The coil 190 extends for a short distance, e.g.,approximately 1 inch, from the end of the tube 180 and is of a suitablysmall outside diameter, e.g, 0.018 inch. The distal end of the core 188extends into a small bore in the atraumatic tip 130′ and is soldered inplace by a lead-free solder. The distal end of the coil 128′ is alsosoldered to the atraumatic tip by a lead-free solder. The atraumatic tip130′ is in the form of a hemisphere of any suitable material, e.g., type300 stainless steel.

[0122] A small sleeve or ring 190 formed of any suitable material, e.g.,plastic or stainless steel, is located on the guide wire 124′immediately proximally of the balloon 126′. This ring serves as a stopmember for the atherectomy catheter 22″. In particular, as theatherectomy catheter 22″ is advanced along the guide wire 124′, with theguide wire 124′ and the guide catheter 24 being held in a fixed positionwith respect to each other and to the patient's vascular system by acradle assembly (to be described later), the rotating working head 32″will be prevented from engaging and perforating the distally locatedballoon by the ring or stop 190. Thus, the advancement of the workinghead along the guide wire to remove the plaque or otherrestriction-forming material in the vessel will not present any dangerof perforating the balloon.

[0123] The console 204 is similar to console 102 described heretoforeand includes various electrical and electronic components, e.g., amicroprocessor and associated circuitry to accomplish the variousfunctions of the system and to display various system parameters. Thus,as can be seen clearly in FIG. 9B, the console 204 includes theheretofore identified peristaltic infusion pump 84 and the peristalticextraction pump 90. Compressed gas, e.g., nitrogen, is provided via line112 from the tank 110. The tank provides the compressed nitrogen viaheretofore identified regulator 74 and associated valve 76 into line 112and from there to line 72. The gas pressure is displayed on a dial ormeter 78 on the front of the console. Control of the turbine'srotational speed is effected by a turbine speed adjustment knob 206 onthe front console. The turbine's speed is displayed on a digital displaypanel 208. An optical signal indicative of the turbine's speed isprovided via a fiber optic line 210A. This line is connected to aconnector 212A on the console. Another fiber optic line 210B isconnected to another connector 212B on the console, whereupon a beam oflight from the console is carried down line 212B to the turbine rotorwhere it is broken or chopped up by the rotating blades. The chopped uplight beam which is indicative of rotor speed is carried back to theconsole via line 210A and connector 212A. Control of the turbine iseffected via a turbine foot control (or hand control, not shown) 114connected via line 116 to a connector 214 on the console.

[0124] A pressure transducer 218 (FIG. 9A) is connected in the line 86coupled from the infusate pump 84 to the atherectomy catheter 22″. Thepressure transducer provides an output signal via a line 220 to aconnector 222 (FIG. 9B) on the console. The rate of infusion liquid flowinto the atherectomy catheter 22″ is effected by the heretoforeidentified peristaltic pump 84. The speed of that pump is controlled viaan up/down switch 224 on the console. The pump's speed in RPM isdisplayed on a digital readout panel 226. The speed of the extractionpump is controlled by an up/down switch 228 on the console and thatpump's speed is displayed on an associated digital readout panel 230.The console also includes an on/off switch 232 for providing electricalpower to the system when the switch is in the on position.

[0125] Data from the console, e.g., operating parameters, etc., isarranged to be downloaded to any suitable device, e.g., a laptopcomputer 216, via conventional multipin electrical connector 218, e.g.,an RS 232 serial port, and associated cable 220.

[0126] If desired, the console 204 may also include various alarmdevices to warn operating personnel of certain abnormal conditions. Forexample, the console may include a low battery power warning lamp on thefront of the console to warn operating personnel that the battery islow. An infusate high pressure warning lamp may also be provided on theconsole along with an associated audible annunciator to producerespective visible and audible warning signals when a high pressureinfusate condition exists.

[0127] Referring now to FIGS. 12 and 13, the details of the atherectomycatheter 22″ will now be described. As can be seen that the catheter 22″is similar to catheter 22′ in that it includes a jacket 34 having adistal end. A rotary working head or tip 32″ is located at the distalend of the jacket. The tip 32 is preferably constructed in accordancewith the teachings of U.S. Pat. No. 4,747,821. However, tip 32″ unlikethe tip of the aforementioned patent includes a central passageway orbore 148 through it (like tip 32). It is through this bore that theguide wire 124 extends.

[0128] The working head 32″ is mounted for rotation within a bushing 302secured to the distal end of the jacket. The bushing 302 is similar inconstruction to the bushing of the U.S. Pat. No. 4,747,821 and itincludes plural passages 46″ extending along its length through whichthe infusate liquid passes to exit out of the tip. In addition itincludes plural radial passageways 304 in the thrust pad portion formingthe distal end of the bushing and which are in communication with thepassages 46″ through which the liquid exits radially. The radialpassages are constructed similarly to those of U.S. Pat. No. 5,049,124(Bayles) whose disclosure is incorporated by reference herein. Thus, theexiting liquid from those passages is impacted by the flattened sides ofthe tip to create a vortex flow in a manner similar to that as shown inFIG. 12. The rotary working head 32″ also includes a tubular shankportion through which the central bore 148 extends. Infusate liquid fromthe passageway 312 is enabled to flow into the open proximal end of thebore 148 and through the annular space or clearance between the innersurface of that bore and the outer surface of the guide wire extendingthrough the bore as shown by the arrows in FIG. 12. A sleeve 306 islocated immediately proximally of the bushing 302 and extends about theshank portion of the rotary working head 32″. The sleeve 306 is weldedto the shank portion of the rotary working head. The rotary working head32″ is arranged to be rotated at a high rate of speed within the bushingby a drive cable 308. As best seen in FIG. 12, the cable 308 is abifilar or double helix formed of any suitable material, e.g., 304stainless steel or Nitinol, and is flexible so that the atherectomycatheter can be readily bent to follow tortuous paths to therevascularization site, i.e., the coronary bypass graft. The distal endhelices of the drive cable 308 are welded at 310 to the shank portion ofthe rotary working head 32″. The outer diameter of the drive cable isless than the inner diameter of the catheter jacket 34 to form anannular passageway 312 therebetween. This passageway extends the fulllength of the atherectomy catheter and serves to carry the infusionliquid to the working head 34″.

[0129] A flexible plastic tube or sleeve 314 is located within thecentral passageway of the bifilar drive cable 308 and extends for thefull length thereof. The tube 314 includes a central passageway 316which is of approximately the same internal diameter as the bore 148extending through the working head 32″ and is coaxial therewith in orderto accommodate the guide wire 124 therethrough. The sleeve 314 serves toform a barrier between the metal helices of the drive cable 308 andmetal guide wire extending through it, while preventing the helices ofthe cable 308 from closing up as the drive cable is rotated.

[0130] In FIG. 13, there is shown the details of the proximal end of theatherectomy catheter 22″. Thus, it can be seen that the proximal end ofthe jacket 34 is flared outward at 318. The flared proximal end of thejacket is connected to the distal end of a turbine housing or body 320via a capture nut 322. The capture nut 322 includes internal threads 324which mate with corresponding external threads on the distal end of theturbine housing 320. The free end of the turbine housing is tapered at326. The capture nut 322 also includes a tapered inner surface 328merging into a central bore 330 through which the catheter jacket 34extends. Thus, when the nut 322 is tightened, the flared end 318 of thejacket is tightly interposed between the surface 330 of the nut and thetapered surface 326 of the turbine housing 320. The distal end portionof the turbine housing 320 also includes a central bore 332 into whichthe infusate fluid will be injected for flow into the annular passageway312 in the atherectomy catheter, as will be described later.

[0131] The proximal end of the bifilar drive cable 308 is connected,e.g., welded, to an adaptor sleeve 334. The adaptor is a tubular memberwhich is in turn welded to the turbine rotor drive shaft 336. Theturbine drive shaft 336 is an elongated tubular member. Being tubularthe turbine drive shaft 336 includes a central passageway. It is throughthis central passageway that the guide wire is arranged to be extended.The turbine rotor drive shaft 336 extends through the central bore 332in the turbine housing and terminates at its proximal end in aseven-bladed turbine rotor 338. The rotor is located in an enlargedproximally located flanged portion 322 of the turbine housing 320. Inparticular, the flanged portion 322 includes a hollow interior chamber340 in which the turbine blade 338 is located. An enlarged central bore342 extends distally of the chamber 340 and is axially aligned with thecentral bore 332 in the distal portion of the turbine housing 320. Asleeve bearing 344 is located within the central bore 342. The turbinerotor shaft 336 extends through a central bore in the bearing with aslight clearance or leakage passageway, e.g., 0.0005 inch, to form afluid leakage path to facilitate the cooling of the bearing. An O-ring346 is located within an annular recess in the distal portion of thesleeve bearing 344 to form a fluid-tight seal. A star washer 348 islocated within an enlarged portion of the bore 342 to hold the sleevebearing in place.

[0132] The proximal end of the turbine drive shaft 336 extends into aball bearing assembly 350 to center the turbine shaft on thelongitudinal axis of the housing. A guide-wire centerer and leakagecontrol restrictor member 352 is located within the hollow proximal endof the turbine drive shaft 336. The guide wire 124 is arranged to passthrough the restrictor where it is centered and then through the turbinedrive shaft, the adaptor 334, the sleeve 314, and out through bore 148in the working head 32″. Moreover, air can pass through the interface ofthe restrictor 352 to cool and lubricate the adjacent surfaces. The ballbearing assembly 350 is held in place via a cap or cover 354. The cap354 serves to close off the hollow interior of the turbine housing. Tothat end, the cap is releasably secured to the flanged proximal portion322 of the turbine housing 320 via plural threaded bolts 356. Anenlarged bore hole 358 is located within the cap 354 and is coaxiallyaligned with the central longitudinal axis of the drive shaft 336. Asmaller diameter bore 360 communicates with the bore 358 and with therestrictor 352.

[0133] The compressed gas, e.g., nitrogen, to effect the rotation of theturbine is provided from the tank 110 via an inlet port 362. Thepressurized gas enters the turbine housing portion 322 somewhattangentially and impinges on the angled rotor blades 338 to cause theturbine rotor to rotate about its longitudinal axis at a high rate ofspeed. This effects the concomitant rotation of the drive shaft 336, thebifilar cable 308 and hence the rotary working head 32″.

[0134] The infusate fluid, e.g., saline and a contrast medium (plusanything else which is desired to be introduced into the vascularsystem, such as heparin, growth factors, microspheres carryingchemicals, pharmaceuticals or other biologically active materials, etc.)is introduced into the turbine housing 320 so that it gains ingress intothe passageway 332. From that passageway, it flows through thecommunicating passageway 312 extending within the jacket of the catheterto exit at the distal end of the jacket where the working head 32″ islocated. The means for introducing infusate liquid into the turbinehousing comprises the tubing 86 on which a connector 362 is mounted. Theconnector 362 is arranged to be connected to the output of the infusatepump.

[0135] An interlock member 366 is located in a transverse bore 368 inthe turbine housing 320 so that it perpendicularly intersects thelongitudinally extending bore 332. The interlock member is a generallyplug-like, tubular body having a thin walled upper end 368 defining anenlarged hollow interior space. An opening 370 is provided in the thinwalled upper end of the interlock member communicating with the enlargedhollow interior space and into which the distal portion of the sleevebearing 344 extends. Another opening 372 is provided diametricallyopposed from the opening 370 so that the turbine drive shaft 336 canextend through the interlock member via the openings 370 and 372. Thelower end of the interlock member 366 includes a barb-like tubularprojection 374 which extends into the interior of the plastic tube 86. Aring-like ferrule 376 extends about the outer surface of the tube at theupper end thereof to capture the tube on the barb. A sealing O-ring 378is disposed within an annular recess extending about the periphery ofthe interlock member 366. The barb portion of the interlock member 366includes a passageway 378 extending through it in communication with thehollow interior at the upper end of the interlock member. Thus, theinfusion liquid introduced into the tube 86 will pass through thecommunicating passageway 378 in the barb member into the hollow upperinterior 368 of the interlock member and out through opening 372 intothe passageway or bore 332. From passageway 332, the infusate liquidwill flow through the hollow annular passageway 312 in the catheter'sjacket 34 and out through its distal end at the working head 32″.

[0136] As will be appreciated by those skilled in the art, the rotationof the drive cable 308 creates an Archimedes-like pumping action to aidthe infusate pump in carrying the infusate liquid down the annularpassageway 312 in the jacket 34. In particular, the ability of thehelical drive cable 308 to deliver flow is a function of: (1) therotation speed of the helix, (2) the swept volume of the helix (theswept volume of the helix being the volume of fluid entrapped betweenthe coils of one pitch of the helix), and (3) the leakage of flow backalong the helix due to the clearance between the helix and the jacketand the clearance between the helix and the liner. If the clearances arereduced to zero (leakage reduced to zero) the pump can act as a verystiff positive displacement pump, that is, it can deliver flow at alarge range of output pressures regardless of the inlet pressure. Forexample, with a 5F diameter catheter having bifilar drive cable with0.008 inch wire diameter and pitch of 0.040 inch running at speedsbetween 100,000 and 160,000 RPM, the helix design suitable fortransmitting suitable torque, with adequate flexibility for navigatingthe bends of the coronary vasculature, also has the correct swept volumeto deliver an appropriate flow, e.g., 30-40 mL/minute, required to keepthe catheter and tip abrasion site at a temperature compatible withtissue viability (e.g., not more than 98 deg F.). These facts make itpossible for a 5F catheter system to use the helical drive cable 308 asthe infusate metering pump while the peristaltic infusate pump 84 servesas a priming pump. This arrangement, can deliver pressure rather thanflow by the use of soft pump tubing, i.e., tubing that leaks back underthe pump 84 rollers, if the delivery pressure becomes excessive, e.g.,approximately 30 psi or greater. If different size catheters are used,such as 8F or 4F, the helical drive cable design may not provide theideal flow, and the peristaltic infusate pump 84 characteristics mightwell have to be changed to obtain the correct flow. This can beaccomplished by changing the peristaltic pump speeds, changing thestiffness of the peristaltic pumps by using tubing of differentsoftness, and partially disabling the helix drive cable pump byincreasing the clearances around the helix. Thus, if the consoleprovides for independently adjustable peristaltic pump speeds for theinfusate and extraction pumps, the system can provide for any catheterdesign. The operator can be instructed to select the appropriate pumpspeed and the appropriate pump tubing for whatever catheter is in use.In some instances it may be advisable to use operator adjustableperistaltic pumps linked electronically that provide for fixed ratiosbetween the infusate and extraction pumps, and in other designs it maybe best to provide for the pumps to be preset and not user adjustable.

[0137] It has also been found that there is an advantage to having avariable pitch helix for the drive cable 308. Thus, the cable 308 ispreferably so constructed. As will be appreciated if the drive cable 308is to act as a pump in addition to the means for effecting the rotationof the working head, the helices of the cable have to have a certainpitch (e.g., 25 coils to the inch) to provide the required swept volume.If the bending stiffness of the atherectomy catheter is to be minimized(e.g., to enable the catheter to freely negotiate tortuous paths to thesite of the occluded vessel section) the helices of the cable needs tobe approximately of closed coil configuration (e.g., 40 coils to theinch), but not quite closed, because it is best if the coils do nottouch each other as the catheter bends since the friction between theabutting coils may cause excessive heat to be generated. It has beenfound that if the distal end portion of the helical drive cable 308 isalmost close wound for a short distance (e.g., 0.5 to 4.0 inches), as isthe case in the embodiment shown herein, the remainder of the cable,(i.e., the portion located proximally of the distal end portion andwhich may be approximately 50 inches or longer) can force the infusateliquid past the close coils at the distal end and out of the catheter.The variable pitch of the drive cable thus provides for the optimumpumping action, while maintaining optimum flexibility. As will also beappreciated the helix pitch of the drive cable also has an affect onvibration of the catheter, with the coarser or greater spacing betweenhelices resulting in lower vibration. Thus, the variable pitch drivecable 308 will also help to reduce the vibration level by minimizing thelength of closed coil helices at the distal end of the drive cable.

[0138] As mentioned earlier, the system 200 includes a cradle assembly202 for holding the guide catheter 24 and the guide wire 124 fixed withrespect to each other and with respect to the patient's vascular system,while supporting a portion of the atherectomy catheter to enable it tobe moved longitudinally with respect to the guide catheter and guidewire in order to advance the working head through the vessel section tobe revascularized. The cradle assembly 202 will now be described withreference to FIG. 9A. As can be seen therein, the cradle assemblybasically comprises a cradle member 400 (shown by phantom lines in theinterest of drawing simplicity) and other associated components (someshown by solid lines and others by phantom lines), all to be describedlater. The cradle member 400 itself is a generally tubular member whichis arranged to support the turbine body therein and to allow the turbinebody to slide longitudinally with respect to the cradle member 400 whilefixing the position of the guide catheter 24 and guide wire 124 relativeto each other.

[0139] The tubular cradle 400 includes a loading slot 402 extending fromits front or distal end to a point close to its rear or proximal end. Apair of support feet 404, also shown by phantom lines, are provided onthe underside of the cradle tube to support it on any horizontalsurface. A cup-shaped plug member 406 is mounted in the open rear end ofthe cradle tube. The plug member includes a central passageway 408extending through it. A pair of telescoping tubes 410 and 412, aremounted between the central passageway in the plug member and theproximally located cap 354 of the turbine housing 320 via a ferrule (notshown). The central passageway 408 in the plug member and the associatedtelescoping tubes 410 and 412 provide a passageway through which theguide wire 124 may be extended into the turbine housing and from therethrough the atherectomy catheter 22″ as described earlier. Thetelescoping tubes are formed of any stiff material, e.g., type 304stainless steel, to prevent buckling of the guide wire.

[0140] In order to fix or clamp the longitudinal position of the guidewire with respect to the cradle assembly while also forming a fluidtight seal about the guide wire where it enters the plug member 406, aconventional hemostasis valve, e.g., a Tuohy Borst valve 412, is mountedon the rear side of the plug member via a wing nut mount (not shown).

[0141] The turbine housing assembly is mounted within the cradle tubefor sliding movement therealong in order to adjust the distance that theworking head 34″ extends from the distal end of the guide tube 24. Thisfeature enables the rotary working head to be advanced in the distaldirection to open a lumen through the plaque or other material formingthe restriction in the bypass graft to be revascularized. To achievethat end, a handle 416 is provided for the turbine housing and projectsradially outward from the turbine housing portion 322. The handleextends through a longitudinally extending linear slot 418 in the cradletube 400. It should be pointed out at this juncture that the handle andthe associated slot are shown on the facing side of the turbine tube(i.e., the visible side in FIG. 9), when in reality they are located onthe opposite side. The showing of the handle and slot on the facing sideof the cradle tube is merely done for drawing convenience.

[0142] In order to increase the “wheel base” of turbine housing so thatit slides easily within the cradle tube 400 in a longitudinal directionwithout tilting or canting, a turbine tube housing extension member 420is mounted, i.e., snap-fit, on the distal portion of the turbinehousing. The extension member 420 includes a central opening throughwhich the atherectomy catheter 22″ exits the turbine housing.

[0143] A manifold member 422 is mounted within an extension adjustmenttube 424 at the front end of the cradle tube 400. The extensionadjustment tube is a slotted tube which telescopes within the front endof the cradle tube 400 and whose position can be adjusted so that themanifold 422 can be moved closer or further away from the cradle tube.This feature enables the system 200 to be used with guide catheters ofvarying lengths. In order to fix the position of the extensionadjustment tube with respect to the cradle tube 400, a tube extensionlatch 426 is provided to extend through any selected one of plurallongitudinally spaced holes 428 in the extension tube and a singlealigned hole not shown in the front end of the cradle tube.

[0144] The manifold 422 is a disk-like member having a longitudinalpassageway (not shown) extending therethrough and to which the proximalend of the guide catheter 24 is connected via a swivel connector 430.The swivel connector permits one to adjust the angular orientation ofthe guide catheter with respect to the cradle tube so that the guidecatheter can be revolved to any rotary position necessary to obtaincompatibility with the patient's vascular anatomy. The longitudinalpassageway of the manifold is in fluid communication with the proximalend of the annular passageway 312 extending down the interior of theatherectomy catheter's jacket. The manifold also includes a radiallyextending side port (not shown) in communication with the longitudinalpassageway at the proximal end of the guide catheter. The extraction(vacuum) tube 88 is arranged to be connected to the radial side port ofthe manifold via conventional connector 432 to withdraw blood, infusateliquid and debris which has been drawn down the passageway between theguide catheter and the atherectomy catheter by the action of theextraction pump 90.

[0145] Since the atherectomy catheter 22″ extends through the guidecatheter 24, a conventional hemostasis valve 434 is mounted on the rear(proximal) side of the manifold 422 to enable to the atherectomycatheter to extend through the longitudinal passageway in the manifoldand into and through the guide catheter 24.

[0146] A stiffener tube 436 is provided on the atherectomy catheterbetween the turbine housing and the manifold to prevent the atherectomycatheter's jacket 34 from buckling under axial loads. The stiffener tubealso facilitates the assembly and loading of the atherectomy catheterinto the cradle tube. To that end, a hook wire 438 is mounted on thestiffener tube 436 to facilitate movement of the stiffener tube. A pairof pivotable trunnions 440 project outward from the distal end portionof the stiffener tube for connection to diametrically opposed portionsof the extension tube 424 to center the stiffener tube so that it can belifted to enable loading of the atherectomy catheter.

[0147] In accordance with one preferred embodiment of the invention, thelongitudinally extending slot 402 is of sufficient length to enable theturbine housing and hence the atherectomy catheter 22″ to bereciprocated through a 4-5 inch range.

[0148] It must be pointed out again that the subject invention is notlimited to atherectomy catheters, and particularly rotary headcatheters. In particular, the subject invention may incorporate aninstrument having any other type of working head, e.g., a balloonangioplasty catheter, a catheter for injecting a restriction-removing ordissolving liquid, an ultrasonic catheter, a laser catheter, astent-delivery catheter, etc., for opening a lumen in an occludedvessel. To that end the term “working head” as used herein is meant toinclude any type of device for operating on an occluded vessel to open alumen in that vessel to the freer flow of blood therethrough.

[0149] In FIGS. 16 and 17 there are shown yet another alternativeembodiment of a revascularization system 500 of this invention. Thesystem 500 is arranged to revascularize an occluded blood vessel, e.g.,a bypass graft 10′, by introducing a conventional expandable stent 502into a lumen formed in the restrictive material of the occluded bloodvessel section, e.g., the bypass graft. If desired, the system 500 mayalso employ the atherectomy catheter and some associated components ofthe system 200 described heretofore to effect the opening of a lumenthrough the material forming the restriction, followed by theintroduction of a stent-delivery catheter (not shown) for carrying thestent 502 in a collapsed state into the lumen created by the atherectomycatheter, and then to expand the stent 502 in that lumen to the stateshown in FIGS. 16 and 17 to ensure that the lumen stays open. Thestent-delivery catheter used in such an application may be of anyconventional type, e.g., a balloon catheter.

[0150] It must be pointed out at this juncture that the system 500 maybe used without an atherectomy catheter, like the catheters describedabove or any prior art restriction-opening device, for initially formingthe lumen through the material forming the restriction. In such analternative application, as will be described later, the system 500makes use of any suitable conventional stent-delivery catheter to carrythe collapsed stent 502 over a guide wire, like guide-wire 124′ or anyother suitable balloon bearing guide-wire, through the restriction inthe occluded blood vessel to an operative position, whereupon thestent-delivery catheter is operated, e.g., its balloon inflated, toexpand and place the stent in position (like shown in FIGS. 16 and 17).

[0151] Irrespective of the manner in which the lumen is created intowhich the stent 502 is placed, the system 500 of this invention makesuse of a debris removal sub-system to remove any particles or otherdebris produced during the revascularization/stenting procedure. Thatdebris removal system may be similar to that described earlier, or anyother suitable type. As shown in the embodiments of FIGS. 16 and 17, thedebris removal sub-system used to remove any particles or debrisproduced during the revascularization/stenting procedure basicallycomprises a guide catheter 24 having at least one control port, likethat described above, and another catheter 504 (to be described later)for delivery of an infusate or irrigation liquid from some pumpingmeans, e.g., an infusate pump 84, into the occluded vessel section, andsome pumping means, e.g., an extraction pump 90, coupled to the interiorof the guide catheter 24 to effect the removal of blood, the infusionliquid and any debris created during the restriction opening procedurefrom the patient. It should be noted that the “other catheter 504” fordelivery of the infusate or irrigation liquid to the situs of the vesselportion being revascularized, may comprise an atherectomy catheter 22″like that described with respect to system 200 when such a system isused to form the lumen into which the stent will be placed, or maycomprise a separate catheter, tube, or conduit, or may comprise a lumenor passageway in the guide catheter 24 separate and apart from thecentral passageway through which the debris, blood and infusate liquidis removed. In the embodiment shown the catheter 504 for carrying theinfusion or irrigation liquid into the situs where the stent is to beplaced basically comprises a simple irrigation tube or catheter formedof a flexible material, e.g., a plastic, and having a central passagewayor lumen extending fully therethrough for carrying the infusate orirrigation liquid from a pump, like pump 84 or any other suitable sourceof irrigation liquid, down the lumen and out of its open end to theoperative situs like shown in FIGS. 16 and 17.

[0152] If it is desired to utilize a system 500 to apply the stent 502into a lumen formed by an atherectomy catheter, e.g., atherectomycatheter 22″, the procedure to be followed basically comprises thefollowing steps. First the guide catheter 24 is placed in position sothat its distal end is located proximally of the restriction to beopened and its control or regulation port(s) 24A/B is(are) in fluidcommunication with an upstream patent vessel, e.g., the aorta, likeshown in FIGS. 10, 11, 16 and 17. The guide wire 124′ is then extendedthrough the guide catheter 24 and through the restriction to be openedso that the distally located balloon (obturator) 126 on the guide wireis downstream of the restriction. The balloon 126 is then inflated toblock the vessel to be revascularized downstream of its restriction. Theextraction pump 90 is then operated to evacuate any debris particleswhich may have been produced by the passage of the guide wire 124 andballoon 126 through the restriction and by the inflation of the balloon126. The atherectomy catheter 22″ is then passed over the guide wirethrough the guide catheter so that its working head 32″ extends out ofthe open end of the guide catheter and is at the situs of therestriction to be opened.

[0153] The atherectomy catheter 22″ (or any other catheter having arestriction opening working head) is then operated in a manner likedescribed above to enable the working head to open a lumen through therestriction, while the debris removal sub-system removes the debriscreated by that operation along with blood and the infusate liquidthrough the guide catheter. The control or regulation ports in the guidecatheter ensure that the vessel being revascularized does not collapseduring the procedure.

[0154] Once the lumen has been created through the restriction, theatherectomy catheter can be removed, while maintaining the vacuum, i.e.,keeping the extraction pump 90 operating . After removal of theatherectomy catheter the extraction pump 90 can be stopped. If it isdesired to give the patient some recovery time before deployment of thestent 502, the distal balloon on the guide wire may be deflated, therebyenabling blood to flow through the newly formed lumen in therevascularized vessel to the downstream vessel, e.g., a coronary artery15. Once sufficient time for the patient to recover has elapsed(assuming that any recovery time is desired) the distally locatedballoon 126 is then re-inflated.

[0155] The stent-delivery catheter (not shown) is then introducedthrough the guide catheter and over the guide wire until its workinghead, e.g., the balloon on which the collapsed stent 502 is located, iswithin the lumen created by the atherectomy catheter 22″. Thestent-delivery catheter is then operated, e.g., its balloon inflated, toexpand the stent 502 radially outward and into seating engagement withthe revascularized vessel section, like that shown in FIGS. 16 and 17.If desired, the debris removal system may be operated to withdraw anydebris particles created by the deployment of the stent. Once the stenthas been deployed the stent-delivery catheter can be removed, e.g., itsballoon deflated and then the catheter withdrawn proximally along theguide wire. The guide catheter can then be removed.

[0156] In some applications it may be desirable to provide an irrigationor infusate liquid into the lumen in which the stent is to be deployedduring or immediately after the stent deployment the procedure. To thatend, an irrigation tube 504 (like that shown in FIGS. 16 and 17) may beintroduced over and along the guide wire 124′ and through the guidecatheter 24 so that its open distal end is in communication with thesitus of the stent while the distally located balloon (obturator) 126′remains inflated. An irrigant liquid can then be introduced via theirrigation tube to flush out any debris via the passageway between itand the guide catheter under the action of the extraction pump 90 or anyother suitable pump or vacuum source. Once this has been accomplishedthe irrigation tube 504 can then be withdrawn over the guide wire, whilethe vacuum is maintained, e.g., the pump 90 operates, to remove anydebris which may be produced by the removal of the irrigation tube. Thevacuum (e.g., pump 90) can then be stopped, the balloon 126′ on thedistal end of the guide-wire 124′ can then be deflated and the guidewire can then be withdrawn through the guide catheter 24. Then the guidecatheter can be removed.

[0157] If it is desired to place a stent 502 within an occluded bloodvessel section, without having first opened a lumen through it with anatherectomy catheter, like catheter 22″ or any other lumen-openingcatheter, the procedure to be followed using the system 500 basicallycomprises the following steps. First the guide catheter 24 is placed inposition so that its distal end is located proximally of the restrictionto be opened and its control or regulation port(s) 24A/B is(are) influid communication with an upstream patent vessel, e.g., the aorta,like shown in FIGS. 10, 11, 16 and 17. The guide wire 124′ is thenextended through the guide catheter 24 and through the restriction to beopened so that the distally located balloon (obturator) 126′ on theguide wire is downstream of the restriction. The balloon 126′ is theninflated to block the vessel to be revascularized downstream of itsrestriction. The stent-delivery catheter (not shown) is then introducedthrough the guide catheter 24 and over the guide-wire 124′ until itsworking head, e.g., the balloon on which the collapsed stent 502 islocated is at the desired position within the vessel to berevascularized. The debris removal sub-system, or any other extractionor vacuum system, is then operated to withdraw any debris or particlescreated when the stent is deployed. Thus, once the debris removalsub-system is operating the stent-delivery catheter can then beoperated, e.g., its balloon inflated, to expand the stent 502 radiallyoutward thereby enlarging the lumen through the restriction seating thestent in place against accidental dislodgement within the blood vesselsection, like that shown in FIGS. 16 and 17. Once the stent has beendeployed the stent-delivery catheter can be removed, e.g., its balloondeflated, and then the catheter withdrawn, e.g., slid proximally alongthe guide-wire 124′ until it is out of the being's body. An irrigationor infusate liquid is then provided into the operative situs, i.e., thesitus of the stent, to flush away any debris created during the stentdeployment procedure. To that end, an irrigation tube 504 is introducedalong the guide wire 124′ and through the guide catheter 24 so that itsopen distal end is in communication with the situs of the stent, whilethe distally located balloon (obturator) 126 remains inflated. Anirrigant liquid can then be introduced via the irrigation tube 504 toflush out any debris via the passageway between it and the guidecatheter 24 under the action of the extraction pump 90 or any othersuitable pump or vacuum source.

[0158] Once the stent is deployed and all debris removed, the irrigationtube can then be withdrawn from the being by sliding it out over theguide-wire 124′, while the vacuum is maintained, e.g., the pump 90operates, to remove any debris which may be produced by the removal ofthe irrigation tube. As described earlier, the control or regulationport(s) 24A/B ensure that the vessel section being revascularized doesnot collapse during the revascularization procedure.

[0159] After removal of all remaining debris, the vacuum (e.g., pump 90)can then be stopped, the balloon 126 on the distal end of the guide-wirecan then be deflated and the guide wire can then be withdrawn throughthe guide catheter. Then the guide catheter can be removed.

[0160] Irrespective of the type of revascularization procedure utilized,it may be desirable before removal of the guide catheter 24 to inject adye through it to the operative situs to enable one to fluoroscope orotherwise visualize the bypass vessel to ensure that it has been beproperly revascularized.

[0161] In FIG. 18 there is shown a preferred embodiment of the overallsystem of this invention. The components of the overall system are giventhe same reference numbers in FIG. 19 as previously used in the interestof brevity and consistency. In FIG. 9b the control system for therevascularization device of this invention is shown in the form of aconsole 204. In FIG. 18 the control system equivalent to the console 9Ais denoted by the reference number 600 and is shown mounted on aroll-about unit 602. The control system 600 has a video display 604 withan associated microphone 606 and loudspeaker 608 and various control(mode or procedure) buttons or switches 610. The revascularizationsystem of this invention is arranged to be operated in various modesunder control of the control system. In particular, it has beendetermined that the values selected by the control for infusate pumpspeed would fall into a few groups related to the particular mode ofoperation of the system. It has also been determined that the operatorhas to carry out preliminary functions, such as priming the catheter toeliminate air bubbles, and priming the extraction tubing for the samereason. The operator also has to flush the operative site afterdeployment of a stent.

[0162] In accordance with one aspect of this invention the system isarranged so that the operator can be guided throughout the procedure bythe use of simple mode buttons 110 and the video display 604 shownmounted on the roll-about unit. This arrangement provides informationabout the sequence of the procedure, the values of important parameters,and provides the operator with some guidance in the case of faultsoccurring based on software included in the system. The table belowillustrates the information that is available to be displayed byselection of the mode buttons 110 of the control system 600 consoleshown in FIG. 18. Display Audible alarm Foot sounds Foot controldepressed control Trouble- Mode Mode Elapsed Infusate Turbine releasedshooting button descrip- time pressure speed Procedural instruc- # tionMinutes psi KRPM instructions tions 1 Prime No Yes Yes Yes Yes catheterif alarm & test speed 2 Prime No No No Yes No extrac- tion 3 Run Yes YesYes Yes Yes catheter if alarm 4 Adjunct No No No Yes No therapy 5 FlushYes No No Yes Yes if alarm

[0163] It should be noted that the right hand column of the above tabledenotes the presence of troubleshooting instructions if an alarm occurs.In a preferred embodiment of this invention an alarm sounds if theinfusate pressure is either too low (indicating a starvation of supplyto the catheter and the danger of damaging tissue) or too high(indicating a blockage with similar consequences). The video display 604could be used in a similar manner for any other alarms conceived.

[0164] In use the operator starts by pressing the “Mode button #1” ofthe buttons or switches 610 and follows the displayed instructions. Whenthe foot control 114 is depressed to activate the pumps 89 and 90 and/orthe turbine 70 the display 604 changes to show only the active values oftime, infusate pressure, and turbine speed. If an alarm sounds thedisplay suggests corrective action.

[0165] As will be appreciated by those skilled in the art the subjectsystem can be expanded to deal with more modes and more signals fromadditional transducers, such as sensors for the degree of filling of theextraction collection bag 92, or temperature of the catheter at the tip.

[0166] One of the significant advantages of this sequential display ofinformation is the ability to use a small display screen and to avoidoverloading the operator with masses of information at once. A furtherimprovement is provided by the subject system including means fordelivering audio instructions to the operator and for accepting voicecommands or information from the operator through the use of voicerecognition means, e.g., hardware and software in the system. Forexample, with such a system, the operator can call out the mode, whichis picked up by a microphone on the console. A voice recognition chipand associated software (not shown) accepts the input, adjustsparameters for pump and turbine speed and then produces audibleinstructions which are delivered to the operator through theloudspeaker. As will be appreciated by those skilled in the art theaudio signals can also be transmitted to the operator by alternate meanssuch as cables, wireless and headphones etc.

[0167] In FIG. 19 there is shown a preferred embodiment of the guidewire124′ with the balloon 126′ mounted thereon. In particular, the guidewire124′ includes a wear resistant coating (not shown) on its outer surfaceto preclude the risk of damage from the rotating tip 32″. The coatingcan be of any hard material that can be deposited in a thin layer. Sucha material must have a tensile modulus which reasonably matches that ofthe tubing from which the guide wire is made if the coating is quitethick or flaking may occur when the wire is bent. Chromium plating (suchas that provided by Me92 Operations Inc. of Providence R.I.) allowsthicknesses of up to about 0.0008 inch to be applied to tubes of 0.010inch outside diameter and allows the tubing to be bent to radii of0.375“or less without flaking of the coating.” Such coatings havehardnesses ranging from 62 Rc-70 Rc, and have a modulus of about 33*10^6 psi which is similar that of the steel tube. If a very thin coating isapplied (e.g., less than 1 u) the coating has to be very hard to resistwear, but can have a bad mismatch in modulus and still allow the tube tobe bent to radii of 0.375 inch or less without flaking of the coating. Acoating of titanium nitride about 2 u thick having a hardness of around80 Rc functions well. Such a coating has a modulus of around 100*10^ 6psi and does not flake although much stiffer than the steel tube at28*10^ 6 psi.

[0168] The guidewire 124′ is also advantageously made from more than onesegment of tubing as seen clearly in FIG. 19. The distal segment 124A′is made from a smaller tube than the proximal tube segment 124B′ and isfixedly secured thereto, e.g., welded, soldered or brazed, within theproximal tube 124B′. This arrangement allows the distal portion of theguide wire to navigate the tortuous coronary vasculature withoutexceeding the elastic limit of the steel tubing. A proximal segment of0.014 inch OD and 0.010 inch ID with a distal segment of 0.010 OD and0.005 ID both segments being of 304 S.S., ¾ hard tube gives the desiredflexibility.

[0169] It is not unusual for a guide wire to be coated with Teflon toprovide for a low friction coefficient at the surface of the wire. Inthe case of the present invention Teflon can be applied to the proximalsection of the guide wire and the hard wear resistant coating can beapplied to the distal section. The combination provides for wearresistance at the distal end and smooth torquing and pushability of theproximal portion.

[0170] Without further elaboration the foregoing will so fullyillustrate our invention that others may, by applying current or futureknowledge, adopt the same for use under various conditions of service.

1. A tubular guidewire for use in an intravascular system for opening alumen in an occluded blood vessel portion of a living being's vascularsystem, the occluded blood vessel portion being occluded by an occlusivematerial and being located downstream of a patent blood vessel portion,the intravascular system comprising a rotary atherectomy instrumenthaving a rotary working head, the instrument being arranged to bemounted on said guidewire and moved with respect thereto so that theworking head is located adjacent the occlusive material, said guidewirehaving a wear resistant coating for reducing wear on the guidewireresulting from the rotation of the rotating working head.
 2. The tubularguidewire of claim 1 wherein said wear resistant coating is chromiumplate.
 3. The tubular guidewire of claim 1 wherein said wear resistantcoating is Titanium nitride.
 4. A wear resistant coating for a tubularguidewire for deployment in the body of a living being wherein theguidewire in bent during its deployment, said wear resistant coatinghaving properties to prevent the flaking thereof when the guidewire isbent to a small radius on the order of approximately 0.375 inch (9.5mm).
 5. A tubular guidewire for use in an intravascular system foropening a lumen in an occluded blood vessel portion of a living being'svascular system, the intravascular system comprising an instrument foropening the lumen in the occluded blood vessel portion and beingarranged to be guided to a desired position by said guide wire, saidguide wire being arranged to be bent during its deployment within thebeing's vascular system and having a wear resistant coating, said wearresistant coating having properties to prevent the flaking thereof whenthe guidewire is bent to a small radius on the order of approximately0.375 inch (9.5 mm).
 6. A tubular guidewire for use in an intravascularsystem for opening a lumen in an occluded blood vessel portion of aliving being's vascular system, the occluded blood vessel portion beingoccluded by an occlusive material and being located downstream of apatent blood vessel portion, the intravascular system comprising arotary atherectomy instrument having a rotary working head, theinstrument being arranged to be mounted on said guidewire and moved withrespect thereto so that the working head is located adjacent theocclusive material, said guidewire having a wear resistant coatinghaving properties to prevent the flaking thereof when the guidewire isbent to a small radius on the order of approximately 0.375 inch (9.5mm).
 7. A wear resistant coating for a tubular guidewire for deploymentin the body of a living being wherein the guidewire in bent during itsdeployment, said wear resistant coating being harder than 58 Rockwell C.8. The wear resistant coating of claim 7 wherein said coating is thinnerthan 0.001 in (0.0254 mm).
 9. A tubular guidewire for use in anintravascular system for opening a lumen in an occluded blood vesselportion of a living being's vascular system, the intravascular systemcomprising an instrument for opening the lumen in the occluded bloodvessel portion and being arranged to be guided to a desired position bysaid guide wire, said guide wire being arranged to be bent during itsdeployment within the being's vascular system and having a wearresistant coating, said wear resistant coating being harder than 58Rockwell C.
 10. The wear resistant coating of claim 9 wherein saidcoating is thinner than 0.001 in (0.0254 mm).
 11. A guidewire for use inan intravascular system for opening a lumen in an occluded blood vesselportion of a living being's vascular system, the occluded blood vesselportion being occluded by an occlusive material and being locateddownstream of a patent blood vessel portion, the intravascular systemcomprising a rotary atherectomy instrument having a rotary working head,the instrument being arranged to be mounted on said guidewire and movedwith respect thereto so that the working head is located adjacent theocclusive material, said guidewire having more than one coating, one ofsaid coatings having wear resistant properties and another of saidcoatings having a low coefficient of friction.
 12. The guidewire ofclaim 11 wherein said low coefficient of friction coating is located ona proximal portion of said guide wire and said wear resistant coating islocated on a distal portion of said guidewire.
 13. An intravascularsystem for use by an operator to open a lumen in an occluded bloodvessel portion of a living being's vascular system, the occluded bloodvessel portion being occluded by an occlusive material, saidintravascular system comprising an instrument for opening a lumen in theocclusive material and a control system, said instrument being arrangedto be extended into the blood vessel portion to a position adjacent theocclusive material in the interior of the occluded blood vessel portionto open a lumen therein for the flow of blood therethrough under thecontrol of said control system, said control system enabling pluralmodes of operation of said instrument and comprising a display and meansfor accepting an audio command regarding a mode of operation to beaccomplished from the operator and for visually displaying that mode ofoperation on said display.
 14. The intravascular system of claim 13wherein said means for accepting an audio command comprises voicerecognition means.
 15. The intravascular system of claim 13 comprising ameans for providing instructions for continuing use of said system tothe operator by said display.
 16. The intravascular system of claim 13wherein said control system is arranged to accept manual inputs theretoto establish said mode of operation.
 17. The intravascular system ofclaim 16 wherein said display displays information about the modeselected by said manual inputs.
 18. The intravascular system of claim 17comprising a means for providing instructions for continuing use of saidsystem to the operator by said display.
 19. The guidewire of claim 11wherein said guidewire is tubular.
 20. The guidewire of claim 12 whereinsaid guidewire is tubular.